Urban farming uses aquaponics to make farmland where there is none

[Eric Maundu] is farming in Oakland. There are no open fields in this concrete jungle, and even if there were the soil in his part of town is contaminated and not a suitable place in which to grow food. But he’s not using farming methods of old. In fact farmers of a century ago wouldn’t recognize anything he’s doing. His technique uses fish, circulated water, and gravel to grow vegetables in whatever space he can find; a farming method called aquaponics.

The video after the break gives an excellent look at his farm. The two main parts of the system are a large water trough where fish live, and a raised bed of gravel where the fish waste in the water is filtered out and composted by bacteria to becomes food for the vegetables. More parts can be added into the mix. For instance, once the water has been filtered by the stone bed it can be gravity fed into another vessel which is being used to grow lettuce suspended by floating foam board. But the water always ends up back in the fish trough where it can be reused. This ends up saving anywhere from 90-98% of the water used in normal farming.

But [Eric] is also interested in adding some automation. About seven minutes into the video we get a look at the control systems he’s working on with the help of Arduino and other hardware.

A lot of grow operations in Oakland have halted after the Feds raided Oaksterdam, which freaked a lot of growers out. Funny story; when looking for some potting soil for succulents I had a hard time finding stores that weren’t exclusively for hydroponics.

Good for them, although there is no lack of tenable farmland in Cali. You are not constrained by city ordinances and neighbors complaints. I read a couple of these stories a month and being from the sticks originally, I can’t help but get a little upset at the folks for having their cake and eating it too. Seems like a lot of these folks have big ideas, but function on an autistic level with the folks around them. Best of luck with the food, city “revenuers”, and Oakland lol.

Yeah, it was in Calif. that some local ordinances forbid clotheslines (in spite of the “green” advantage) and some covenants required cedar shakes (thick shingles) in their respective neighborhoods to maintain the “beauty” of the housing.

I just moved to Oakland a year ago. The level of poverty and desperation paired total lack of access to anything but fast food and liquor stores (seriously) in some parts of the city has shocked my Boston sensibilities (never mind the ugly racism that festers just under the surface out East.) At times it appears as if the Oakland police are actually at war with their less monied citizens. So in my eyes any indigenous and self reliant solution is a great thing.

My on topic question is if there will be elevated levels of toxins in the fish? For example, one serving farmed Atlantic salmon can have 11 times the level of dioxin then the same serving of wild salmon. In general aquaculture is a dubious practice and I wonder if doing it on a small scale is an improvement?

I’ve always read it like this – Hydroponics is growing plants without soil…letting the roots dangle in a constant spray or stream of water and nutrients. Aquaponics was raising fish in controlled environments…like ponds or buckets or net cages in the ocean.

Not sure what the name for it is, if you combine the two…I’ve run across both. We need a third ancient word for water…or a word for water squared.

It’s a good start. This coupled with some of the solar/wind/thermal power solutions we’ve seen could provide a true small-scale off-grid solution.

I wonder how this would scale? In order to sustain a family of 4 you would need a fairly large pond (1/2 acre, 6′ deep or more) stocked with trout, catfish, tilapia, or other reasonably large staple fish. That would produce MUCH more waste, requiring a larger hydroponics setup.

Maybe a large U-shaped trough with water pumped in at one end (near the pond – easier on the pump) and drained out at the other?

A friend of mine is doing this in his back yard with a set of 500 gallon tubs and some trout from a local hatchery. So far he has spent relatively little on the setup, and his plants are growing rapidly. It’s quite an ingenious way to make use of resources, in my opinion.

I would be VERY interested to hear more about your friends setup – how are the trout doing in the relatively small pond? How many does he stock? Do they survive the winter (if it freezes in your area)? Please encourage your friend to write in with a submission – I would love some details, costs, and build notes!

There are definitely problems with that setup – with 500 gallon drums you’ll never end up with any surviving fish fry, so the fish will have to be restocked annually (or more often, if you eat a lot of fish).

He’s only just started it this year, and it’s still in the experimentation stage. He also has no intention of breeding the trout, they are probably all going to end up on the dinner table (they are only $2 each at the local hatchery). If any do stay in the tank, they should winter just fine as he plans on keeping the water circulated to prevent complete freeze-through. The trout are native to this area, so winter shouldn’t be much of a problem for them.
I actually just came from his house and looking over his setup. He has about a dozen trout ranging from 7″ to 11″, and they appear to be thriving. His plants are thriving also, growing faster than the ones in his regular gardens.
As for costs, I really don’t know. Sorry.

Cool, it’s nice to see Erik featured here! I did a workshop with him last year for Workshop Weekend following Maker Faire. Erik’s a very enterprising guy.

Aquaponics are fascinating: you’re basically growing an ecosystem, inputting fishfood and light. However he explained that getting to a stable system is hard, and will take months for your “live rock” featuring healthy nitriting and nitrating bacteria colonies to be good. You’ll spending a long time with your chemistry set trying to stabilize the different parameters.

so after having grown vegetables hydroponically for a couple of summers and moving back to an organic dirt garden this year the food to space/$$/effort ratio on hydroponics is so much better I’m swearing off rototillers for life.

you can make hydroponics as complex or simple as you like, I’v found simple to be plenty good for producing more food than we could consume.

get a sturdy second hand shipping create preferably ~3’x3’x6+’ and line with plastic that’s your holding tank. Find a way to recess the lid 6 inches, line with plastic and fill with gravel that’s your grow bed. Now all you have to do is install a water fountain pump and poke some drainage holes.

Interesting how hydroponics do not need dirt. The only “problem” with it is it requires constant maintenance as the plants grow like mother*******. What I really dig about these setups is the automatisation, now how about an automatic harvester?

now figure out how to cover all rooftops, walls and other exterior dead surfaces with life.

fact: every human’s weight in active life forms means one more human this planet will support. everything we cover with asphalt goes from life-supporting to non-life-supporting. therefore, to save ourselves we must make this planet so it’s BRIMMING with life.

what’s the challenge there? water is scarce. it has to be brought in, plants and things need to be brought up slowly, and once they go up they will be able to help maintain the water within the local ecosystem — a much needed boost in population support.

I have six heavily planted aquariums. The only differences between what I have and this, is that my plants are grown completely submersed; and everything is ornamental rather than for food.

So I can say from experience that this isn’t as closed a system as it might appear.

Obviously, you have to provide fish food. If you have enough fish and enough food, fish waste can easily provide all the nitrogen and phosphorus the plants require.

But fish food alone will not support healthy plant growth. It typically contains very little potassium, which plants need lots of. So you have to add that separately, typically in chemical form as K2SO4 (sulfate of potash).

And it usually doesn’t provide enough of all the other elements required in trace quantities, like iron. So you also have to add micronutrients, typically in a premixed blend like Plantex CSM+B.

Assuming you have enough of all nutrients for continued healthy plant growth, some will accumulate because they’re not consumed as quickly as they’re added. Unfortunately, harmful levels of some nutrients are much lower for fish than for plants.

In a large-scale, commercial operation, it’s practical to test every nutrient level, and adjust the inputs to keep levels in acceptable ranges for long periods of time. Water changes are performed only infrequently.

This isn’t possible for hobby-scale operations. Instead, accumulation is typically addressed by regular and frequent water changes to remove accumulated excesses, and addition of even more chemical fertilizers; which in tandem force levels towards desired ranges. This means more water consumption, and more nutrients going into the wastewater system. Alternately, the discarded water can go on your lawn and soil gardens; but I don’t see any around in the video.

I’m not trying to knock this idea, and as far as hobbies go, caring for little ecosystems is both enlightened and rewarding; especially if it can also put food on your table. But realistically, scale works against you; and small operations tend to have disproportionately higher environmental impacts that are hard to overcome.

Everything you mentioned can be an issue, but chemical fertilizers are not needed under close monitoring. A comprehensive local build that I found after this post piqued my interest gives a painstaking walkthrough of what is needed to start an aquaponics system, from construction to operation:http://www.urbanaquaponics.com/blog.php?1-nwestwood/page4

Don’t expect to simply build a fish pond, a planter, and expect to sit back and harvest your own veggies. Successful operation requires some combination of time, money, and experience. Expect to pay for a lack in any one of those with more of the others.

I browsed it, and it looks very informative. But a bad example to back up your claim that chemicals aren’t necessary.

From part #16, “Plant Deficiencies”, he states he’s having to add magnesium sulfate, potassium sulfate, chelated iron, and calcium nitrate. Plus a lot of phosphoric acid to keep the pH down enough to keep nutrients chelated and available to plants. All chemical ferts, including two I specifically mentioned.

…D’oh! Yes, I suppose if you count mineral supplements as chemicals then they would be required. Of course, I’m not sure how else you would grow – even organic gardening fortifies the soil, the primary difference is the material used to fortify.

The link does show how you would would avoid (or at least minimize) water waste. I’d like to see metrics on how much water these projects add each week (or day, or whatever) for reference.

Well, one other difference is that in small-scale soil gardening, any excess nutrients tend not to directly enter waterways or wastewater streams.

Not a big deal for the occasional home aquaponic setup. But if this were to achieve the popularity of the Victory Gardens in World War I/II, then it could be a serious problem. Which will probably be dealt with by the lawmakers.

After all, it was just two years ago that new legislation in a few US states, intended to reduce phosphates in wastewater, caused dishwashing powder manufacturers to silently remove phosphates from their product nationwide. Resulting in many people wondering why their dishes suddenly weren’t getting clean, and their aluminum cookware was tarnishing. Some people reacted by mixing trisodium phosphate in to fix the problem. I wonder if it’s going to be banned now?

You can have buildups in soil too. Local agencies will usually test soil for free.

But no such luck with aquaponics. A good water test is $45-$60 if I recall. And home testing is inaccurate, incomplete, and many of the tests kits are expensive.

It’s a shame that this practice produces such heavy concentrations of waste byproducts that need to go somewhere.

Also, it looks great, but after zooming through five days of various forums, it seems like the local environmental impact is pretty large, especially in regards to water renewal and disposal. They are very labor intensive, and require a substantial investment if you want to automate your setup.

And I say that as a guy who thinks nothing of pulling out a control system and replacing it with a PC.

Net energy consumption in non-temperate climates can be awfully high – and water evaporates very quickly in large systems, requiring frequent additions of fresh water. I wonder if people realize just how fast anything with leaves can transpire water – it’s a lot, and more than simple evaporation when it’s warm out.

I’d be interested in knowing if the water can be spiked with various chemical precursors, such as acids and minerals (let’s call them vitamins, as everyone else does) and thus punch up the nutritional value of the produce.

When I garden organically, I use other plants to fortify the soil. Every off season I grow things that will fix nitrogen and other nutrients, then dry them out, mulch them and till them into the soil. I’m not sure if I’ve got all the nutrients covered, but I keep getting healthy green beans and potatoes out of the land so I remain happy!

Can’t wait to see if he posts some of his work as open source. Biggest factor to deal with in AP is monitoring water, fish and plants. Being able to automate those would definitely help with peace of mind.